Polyfill MouseEvent Path for Firefox

//It's not available, but if you really would like to have this property, 
//then you could extend the native prototype of the Event object like so:

if (!("path" in Event.prototype))
Object.defineProperty(Event.prototype, "path", {
  get: function() {
    var path = [];
    var currentElem = this.target;
    while (currentElem) {
      path.push(currentElem);
      currentElem = currentElem.parentElement;
    }
    if (path.indexOf(window) === -1 && path.indexOf(document) === -1)
      path.push(document);
    if (path.indexOf(window) === -1)
      path.push(window);
    return path;
  }
});

Ref: http://stackoverflow.com/questions/36845515/mouseevent-path-equivalent-in-firefox-safari